Differential energy expenditure is involved in the difference in activity levels between the Djungarian hamster (Phodopus sungorus) and the Roborovskii hamster (P. roborovskii)

The Djungarian hamster (Phodopus sungorus) shows calm behavior, while the Roborovskii hamster (P. roborovskii) exhibits hyperactivity. Even though they belong to the same genus, Phodopus, these two species are quite different. The current study investigated the relationship between energy expenditure and the markedly different levels of activity shown by these hamsters. Roborovskii hamsters showed significantly higher energy expenditure than Djungarian hamsters under both feeding and fasting conditions during darkness. Roborovskii hamsters showed a repeated increase and decrease in energy expenditure under the feeding condition; however, this changed under the fasting condition, during which the repeated increase and decrease in energy expenditure corresponded to the repeated active and sleeping conditions. Djungarian hamsters had a tendency to keep their energy expenditure constant during the fasting condition, while Roborovskii hamsters moved around a lot to find food. The respiratory quotient (RQ) values in Djungarian hamsters were relatively constant. However, Roborovskii hamsters showed a wide variation in RQ. In particular, the RQ value declined immediately before a dark phase commenced, indicating a switchover from the utilization of glucose to that of lipids as a substrate for energy production. In conclusion, Djungarian hamsters and Roborovskii hamsters showed different behavioral patterns that were related to differences in energy metabolism.

The Greater Impact of Paternal, Compared to Maternal, Hereditary Background on Depressive-Like Behavior in Wistar Kyoto Rats with Different Amino Acid Metabolism in the Pup Brain

In the pathogenesis of depression, heredity is believed to be a major factor. However, the mechanism by which heredity contributes to the onset of depression is not fully understood. Wistar Kyoto (WKY) rats have been used as an animal model for depression because of their increased depression-like behavior compared to Wistar (WIS) rats. In the present study, pups crossbred from WKY × WIS rats were used to evaluate locomotor activity in an open field test (OFT) and depression-like behavior in a forced swimming test (FST), with a focus on amino acid metabolism. Pups in the WKY♂ × WKY♀ group showed lower locomotor activity in the OFT and higher depression-like behavior in the FST than those in the WIS♂ × WIS♀ group. In addition, multiple regression analysis showed that the paternal strain had a greater effect than the maternal strain on locomotor activity and depression-like behavior in OFT and FST, respectively. Several amino acids in the brainstem, hippocampus, and striatum were significantly decreased through the influence of the WKY paternal strain, but not the WKY maternal strain. Based on these data from comparing WKY and WIS rats, we hypothesize that the hereditary effects of the WKY paternal strain on behavioral tests are partially caused by dysregulation of the amino acid metabolism in the brain.

Supplementation of L-Ornithine Could Increase Sleep-like Behavior in the Mouse Pups

Along the maternal-fetal-neonatal axis, one of the problems relating to the maternal-neonatal axis is infant sleep problems including nighttime crying. One possible solution could be to provide the newborn with sleep-promoting ingredients through breast milk or formula. So far, it has been reported that L-ornithine has a sleep-related effect. Therefore, we investigated the effect of dietary L-ornithine on maternal mouse plasma and milk L-ornithine levels in Experiment 1. In Experiment 2, a single dose of L-ornithine was applied to know the time-course changes in plasma, mammary gland and milk L-ornithine levels. Experiment 3 was conducted to confirm sleep behavior as well as changes in polyamine levels in milk. L-Ornithine levels in maternal plasma significantly increased by both dietary regimen and single oral administration in Experiments 1 and 2. Both L-ornithine treatments also increased its levels in milk, although not to a concentration as high as in plasma. In Experiment 3, the level of polyamines, which are metabolized from L-ornithine, did not significantly differ after L-ornithine administration. In sleep-like behavior observations, the average concentration of L-ornithine in milk did not increase the sleep-like behavior of mouse pups. However, more concentrated L-ornithine solutions can significantly increase sleep-like behavior. These results revealed that even if mothers ingested L-ornithine to increase L-ornithine levels in breast milk, it is difficult to promote sleep in newborns. Because it is difficult to raise L-ornithine in breast milk to sleep-inducing levels, L-ornithine added formula may partially improve infant sleep and has the potential for preventing infant sleep problems such as nighttime crying.

A new and efficient method for producing food ingredients high in l-ornithine using unused parts of white cabbage (Brassica oleracea var. capitata)

A surplus of unused parts of vegetables (e.g., white cabbage [cabbage] cores and outer leaves) is generated daily by factories of fresh-cut vegetables. These parts are difficult to effectively utilize and are often discarded as biodegradable industrial waste. This study aimed to develop an efficient method for producing l-ornithine from cabbage residues. First, we added protease (Sumizyme FP) to the cores and outer leaves of sterile cabbages. After 8 days, the amount of l-arginine released was approximately fivefold the amount in the initial content. As l-arginine is a precursor of l-ornithine, the addition of protease combined with Pediococcus pentosaceus produced l-ornithine. However, the rapid lactic acid fermentation suppressed the metabolism of l-arginine to l-ornithine, which we overcame by adjusting the pH by adding eggshell. The anaerobic fermentation of the cores and outer leaves of sterile cabbages with 5% eggshell for 8 days produced 184 ± 2 μmol of l-ornithine/100 g cabbage. PRACTICAL APPLICATIONS: This level of l-ornithine production is higher than that observed in freshwater clams (81-116 μmol/100 g), which are considered to be high in l-ornithine. This method can be applied to the production of inexpensive and safe l-ornithine-containing food materials derived from vegetables. Furthermore, ingestions of vegetables fermented by this method would provide a variety of health benefits of l-ornithine. The widespread adoption of this method will not only reduce the amount of waste generated daily from fresh-cut vegetable factories, but will also enable upcycling as a higher value-added food material.

Thermal manipulation modifies embryonic growth, hepatic free amino acid concentrations, and hatching performance in layer-type chicks

Thermal manipulation (TM) of incubation temperature has been demonstrated to alter metabolism and post-hatch thermotolerance in broiler strains (meat-type chickens). Fewer reports were focused on layer-type chickens and there was no report on amino acid metabolism during TM in layer-type embryos. In this study, we investigated the effects of TM on embryonic development, hepatic amino acid metabolism, and hatching performance in layer-type chickens. Fertilized eggs were incubated under control thermoneutral temperature (CT, 37.6°C) and TM with high temperature (TMH, 39°C, 8 h/day) or low temperature (TML, 20°C, 1 h/day) from embryonic day (ED) 8 to ED 15. The embryonic weight and relative embryonic weight (yolk-free embryonic weight to the initial egg weight) significantly declined in the TML group at ED 13 (P < 0.01) and ED 16 (P < 0.0001), and were significantly increased (P < 0.001) in the TMH group at ED 16, in comparison with the embryos in the CT group. The concentrations of all hepatic free amino acids were significantly increased (P < 0.01) with embryonic development. Interestingly, TMH and TML caused similar effects on hepatic amino acid metabolism, in which most of the essential and non-essential amino acids were significantly declined (P < 0.05) under TM treatments at ED 13 but not affected at ED 16. Until hatching, TML, but not TMH, caused a significant (P < 0.05) delay (31-38 min/day from ED 8) in incubation duration. The hatchability in the TML group was lower than the other two groups, which indicated that 20°C as cold stimulation was not suitable for layer embryos. The body weight, yolk weight, yolk-free body mass, and chick quality were not affected by TM treatments. However, the relative weight of the liver, but not the heart, was significantly reduced (P < 0.05) at hatching by TML treatment. In conclusion, TML, but not TMH, caused to delay in embryogenesis and affected the internal organ of chicks at hatch. Similar changes in amino acid metabolism under TMH and TML indicated that thermal stress induced by both high and low extreme ambient temperatures influences embryonic amino acid metabolism in a similar fashion in layer-type embryos.

Temporal patterns of increased growth hormone secretion in mice after oral administration of L-ornithine: possible involvement of ghrelin receptors

l-Ornithine is known to stimulate growth hormone (GH) release in mammals. Here, we demonstrated that increases in plasma GH levels after oral administration of l-ornithine were first observed 150 min after administration, and the elevated levels were sustained for more than 90 min in mice. The increase was significantly delayed compared with the reported timing of plasma and tissue levels of l-ornithine after administration. The l-ornithine-induced increase in GH release was completely blocked by [D-Lys³]-GHRP-6, a ghrelin receptor antagonist, but not by cyclosomatostatin or JV-1-38, antagonists of somatostatin and GH-releasing hormone, respectively. These results suggest the involvement of ghrelin receptor-mediated pathways in l-ornithine-induced increases in GH release.

Central administration of neuropeptide Y reduces the cellular heat stress response and may enhance spleen antioxidative functions in heat-exposed chicks

Previously it was found that mRNA expression of neuropeptide Y (NPY) was increased in the chicken brain under heat stress. NPY has also been reported as an anti-stress factor to regulate brain functions in heat-exposed chicks. However, to the best of our knowledge, there is no report on the action of central NPY in the immune organs under heat stress. The aim of this study was to examine whether central injection of NPY can regulate heat stress response in the spleen and liver. After intracerebroventricular (ICV) injection of NPY, chicks were exposed to control thermoneutral temperature (CT: 30 ± 1 °C) or high ambient temperature (HT: 35 ± 1 °C) chambers for 60 min. Central injection of NPY caused lowering in rectal temperature under CT, but not under HT. Moreover, ICV injection of NPY caused a significant lower mRNA expression of heat-shock protein-70 and higher expression of glutathione synthase in the spleen, but not liver. Furthermore, plasma uric acid concentrations were significantly increased by the ICV injection of NPY in chicks under HT. These results indicate that brain NPY may contribute to attenuate the intracellular heat stress response and enhance antioxidative status in the immune organ, spleen in chicks.

Intracerebroventricular injection of taurine induces hypothermia through modifying monoaminergic pathways in chicks

Brain monoamines are reported to regulate body temperature and food intake. The objective of this study was to investigate the mechanism of brain monoamine metabolism in taurine-induced hypothermia and appetite suppression. In Experiment 1, 5-day-old male Julia layer chicks (n = 10) were subjected to intracerebroventricular (ICV) injection with saline or taurine (5 μmol/10 μL). In Experiment 2, the chicks were ICV injected with saline, taurine, fusaric acid (dopamine-β-hydroxylase inhibitor: 558 nmol), or taurine with fusaric acid. In Experiment 3, the chicks were ICV injected with saline, taurine, para-chlorophenylalanine (PCPA, tryptophan hydroxylase inhibitor: 400 nmol), or taurine with PCPA. In Experiment 4, the chicks were ICV injected with saline, taurine, clorgyline (monoamine oxidase inhibitor: 81 nmol), or taurine with clorgyline. Central taurine lowered rectal temperature at 30 min post-injection and increased norepinephrine in the brainstem and its metabolite 3-methoxy-4-hydroxyphenylglycol in both the diencephalon and brainstem. Similarly, taurine treatment induced increases in serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid in the diencephalon. Fusaric acid completely and PCPA partially, but not clorgyline, attenuated taurine-induced hypothermia. The anorexigenic effect of taurine was partially attenuated by PCPA, but not fusaric acid nor clorgyline. In conclusion, central taurine activates dopamine-β-hydroxylase and tryptophan hydroxylase to produce norepinephrine and 5-HT, and then induces hypothermia, but 5-HT alone may be linked with taurine-induced anorexia in chicks.

Oral Administration of L-Citrulline Changes Brain Free Amino Acid and Monoamine Metabolism in Heat-Exposed Broiler Chickens

High ambient temperatures (HT) in summer are becoming more severe due to global warming, leading to severe adverse effects on poultry production. Recently, we have reported that oral administration of L-citrulline (L-Cit) can minimize hyperthermia in chickens under HT. However, whether oral L-Cit can enter the brain, the center for thermoregulation, has not been studied. We investigated the effects of oral administration of L-Cit on free amino acids and monoamines in the diencephalon region of the brain of heat-exposed broilers. Broilers were treated with L-Cit (40 mmol/20 ml/bird), then moved to a chamber at HT (30 ± 1°C) or to a thermoneutral temperature (CT: 22 ± 1°C) chamber for 2 h. Control groups were given methyl cellulose solution and placed in the CT or HT chambers. After 2 h of exposure to HT, there were increased brain concentrations of Cit in comparison with concentrations in broilers exposed to CT, whereas brain ornithine (Orn) concentrations were decreased, and arginine (Arg) concentrations were not changed. Interestingly, oral administration of L-Cit increased brain concentration of Cit, Arg, and Orn under both CT and HT. Tryptophan and its metabolite, serotonin (5-HT) concentrations were lower in the brain under HT than under CT. HT did not change brain concentrations of tyrosine, but dopamine (DA, a metabolite of tyrosine) concentrations decreased, and methoxyhydroxyphenylglycol (MHPG, a metabolite of DA) concentrations increased in comparison with CT. Oral administration of L-Cit decreased brain concentrations of both tryptophan and tyrosine under CT and HT without changing 5-HT; however, DA levels declined under HT. Moreover, MHPG concentrations increased. In conclusion, these results suggest that metabolism of amino acids and metabolism of DA can be enhanced in the brain by oral administration of L-Cit. Metabolic changes in the brain in response to oral administration of L-Cit may influence the thermoregulatory center in the brain, leading to a reduction in body temperature and conferring thermotolerance in heat-exposed broiler chickens.

Repeated restraint stress modifies fatty acid and amino acid metabolism in the mouse skin

In modern society, stress caused by relationships and emotions is one of the greatest social problems. Similar to humans, domestic and captive animals live under various stresses. Several stresses have been associated with skin disorders, such as atopic dermatitis, but there is a lack of reliable and objective indicators for the characterization of this association. This study aimed to define the changes in fatty acid composition and amino acid concentration in the skin following repeated restraint stress in ICR mice. Mice subjected to 30 min of daily restraint stress for 8 days showed changes in the composition of saturated fatty acids, such as an increase in palmitic acid content, which are the substrates of Δ-9 desaturase. Conversely, unsaturated fatty acids decreased with stress treatment, which appeared to be a result of these fatty acids being the substrate of Δ-6 desaturase. Changes in fatty acid composition after stress treatment may be one of the factors that cause skin inflammation. The water-retention capacity may have been lowered by stress treatment because histidine and leucine, which are natural moisturizing factors, were significantly decreased. The collagen content in the skin gradually decreased after repeated stress treatment. Our results indicate that repeated restraint stress may impact skin health through changes in both the fatty acid composition and amino acid concentration in mice.

Central Taurine Attenuates Hyperthermia and Isolation Stress Behaviors Augmented by Corticotropin-Releasing Factor with Modifying Brain Amino Acid Metabolism in Neonatal Chicks

The objective of this study was to determine the effects of centrally administered taurine on rectal temperature, behavioral responses and brain amino acid metabolism under isolation stress and the presence of co-injected corticotropin-releasing factor (CRF). Neonatal chicks were centrally injected with saline, 2.1 pmol of CRF, 2.5 μmol of taurine or both taurine and CRF. The results showed that CRF-induced hyperthermia was attenuated by co-injection with taurine. Taurine, alone or with CRF, significantly decreased the number of distress vocalizations and the time spent in active wakefulness, as well as increased the time spent in the sleeping posture, compared with the saline- and CRF-injected chicks. An amino acid chromatographic analysis revealed that diencephalic leucine, isoleucine, tyrosine, glutamate, asparagine, alanine, β-alanine, cystathionine and 3-methylhistidine were decreased in response to taurine alone or in combination with CRF. Central taurine, alone and when co-administered with CRF, decreased isoleucine, phenylalanine, tyrosine and cysteine, but increased glycine concentrations in the brainstem, compared with saline and CRF groups. The results collectively indicate that central taurine attenuated CRF-induced hyperthermia and stress behaviors in neonatal chicks, and the mechanism likely involves the repartitioning of amino acids to different metabolic pathways. In particular, brain leucine, isoleucine, cysteine, glutamate and glycine may be mobilized to cope with acute stressors.

Neuropeptide Y modifies a part of diencephalic catecholamine but not indolamine metabolism in chicks depending on feeding status

The role of the monoaminergic system in the feeding behavior of neonatal chicks has been reported, but the functional relationship between the metabolism of monoamines and appetite-related neuropeptides is still unclear. This study aimed to investigate the changes in catecholamine and indolamine metabolism in response to the central action of neuropeptide Y (NPY) in different feeding statuses and the underlying mechanisms. In Experiment 1, the diencephalic concentrations of amino acids and monoamines following the intracerebroventricular (ICV) injection of NPY (375 pmol/10 μl/chick), saline solution under ad libitum, and fasting conditions for 30 min were determined. Central NPY significantly decreased L-tyrosine concentration, the precursor of catecholamines under feeding condition, but not under fasting condition. Central NPY significantly increased dopamine metabolites, including 3,4-dihydroxyphenylacetic acid and homovanillic acid (HVA). The concentration of 3-methoxy-4-hydroxyphenylglycol was significantly reduced under feeding condition, but did not change under fasting condition by NPY. However, no effects of NPY on indolamine metabolism were found in either feeding status. Therefore, the mechanism of action of catecholamines with central NPY under feeding condition was elucidated in Experiment 2. Central NPY significantly attenuated diencephalic gene expression of catecholaminergic synthetic enzymes, such as tyrosine hydroxylase, L-aromatic amino acid decarboxylase, and GTP cyclohydrolase I after 30 min of feeding. In Experiment 3, co-injection of α-methyl-L-tyrosine, an inhibitor of tyrosine hydroxylase with NPY, moderately attenuated the orexigenic effect of NPY, accompanied by a significant positive correlation between food intake and HVA levels. In Experiment 4, there was a significant interaction between NPY and clorgyline, an inhibitor of monoamine oxidase A with ICV co-injection which implies that co-existence of NPY and clorgyline enhances the orexigenic effect of NPY. In conclusion, central NPY modifies a part of catecholamine metabolism, which is illustrated by the involvement of dopamine transmission and metabolism under feeding but not fasting conditions.

Spermidine resets circadian clock phase in NIH3T3 cells

Irregular light-dark cycles desynchronize the circadian clock via hormonal and neuronal pathways and increase the risk of various diseases. This study demonstrated that a single pulse of spermidine-a polyamine-strongly induced circadian phase advances in the presence or absence of dexamethasone (a synthetic glucocorticoid) in NIH3T3 cells transfected with the Bmal1 promotor-driven luciferase reporter gene. The spermidine-induced phase advances were 2-3 fold greater than were the dexamethasone-induced shifts. The phase resetting effect of spermidine occurred in a dose- and time-dependent manner and was not blocked by RU486, an antagonist of glucocorticoid receptors. Spermidine treatment modulated the expression of clock genes within 60 min, which was sooner than changes in the expression of autophagy-related genes. These findings suggested that spermidine is a potent modulator of the circadian phase, acting through glucocorticoid receptor-independent pathways, and may be useful for treating diseases related to circadian desynchrony.

Effect of regular and irregular stimulation cycles of dexamethasone on circadian clock in NIH3T3 cells

Animal studies have shown that irregular light-dark cycles cause circadian desynchronization, while few studies have addressed the effect of regular/irregular stimulation cycles of signaling hormones on the cellular clock in vitro. Here, we examined how cellular clocks respond to regular and irregular stimulation cycles of dexamethasone, using NIH3T3 cells transfected with the Bmal1 promoter-driven luciferase (Bmal1-Luc) reporter gene. Cyclic stimulation with dexamethasone at different time intervals (18-28 h, 3 times regularly) revealed that Bmal1-Luc bioluminescence rhythms can be entrained to 22 and 24 h cycles during the stimulation period, but not to other cycles. The rhythm entrained for 24 h cycles persisted for at least one day after the last stimulation. Irregular dexamethasone treatment (16, 24, and 16 h, sequentially; short-term jet lag protocol) resulted in an overall upregulation and phase shifts of the temporal expression of several clock genes and cell cycle genes, including c-Myc and p53. Regular dexamethasone stimulation three times with 24 h cycles also caused upregulation of Per1 and Per2 expression, but not c-Myc and p53 expression. In conclusion, our study identified the entrainable range of the circadian clock in NIH3T3 cells to the dexamethasone stimulation cycle and demonstrated that irregular dexamethasone treatment could disturb the expression of cell cycle genes.

Dysregulated metabolism and behaviors by disrupting gut microbiota in prenatal and neonatal mice

The live microbiota ecosystem in the intestine plays a critical role in maintaining the normal physiological and psychological functions in both animals and human beings. However, the chronic effect of microbiota disturbances during prenatal and neonatal developing periods on animal's health remains less studied. In the current study, pregnant ICR mice were fed with an antibiotic diet (7-g nebacitin [bacitracin-neomycin sulphate 2:1]/kg standard diet) from day 14 of conception, and their offspring were provided with the same diet till the termination of the experiments. Dams treated with antibiotics showed increased body weight along with enlarged gut. Antibiotic-treated offspring revealed decreased bodyweight, increased food, water, and sucrose intake. Administration of antibiotics affected corticosterone responsivity to acute 20 min restraint challenge in male pups. In behavior tests, female pups showed decreased movement in open field while male pups revealed decreased latency to open arms in elevated plus maze test and immobility time in tail suspension test. Together, these results suggested that early antibiotic exposure may impact on the food intake, body weight gain, and emotional behavior regulation in mice.

Optimal liver metabolism and proliferation require the tight junction protein claudin-3

Objective

The expression of hepatic tight junction proteins and their contribution to homeostasis and regeneration remained largely unexplored. Here, we determine the cell type specific expression of tight junction genes in murine livers. We further explore the regulation and functional importance of the transmembrane protein CLDN3 in normal and regenerating livers.

Methods

Murine livers were used for tissue- and single cell RNA-seq. CLDN3 localization was determined by immunofluorescence. CLDN3+/+ or CLDN3-/- livers were analysed by electron microscopy, fluorescence-activated cell sorting and liquid chromatography mass spectrometry. Lipid content was quantified with oil-red. Mice were subjected to 2/3 partial hepatectomy. Proliferation was quantified with Ki67 and pHH3 stainings. Cell cycle gene expression was determined by RT-qPCR. Barrier impairments were assessed with total bile acid measurements. Differential gene expression was analysed by tissue RNAseq with DESeq2.

Results

We determined the profile of tight junction gene expression the main liver cell types, showing that tight junction transcripts can be found in hepatocytes and cholangiocytes but also on non-parenchymal cell populations. CLDN3 was among the highly expressed- and regulated genes in native and regenerating livers. CLDN3 had a zonated expression pattern. CLDN3-/- mice had microscopically intact tight junctions, but showed significantly downregulated hepatic energy metabolism and suboptimal cell proliferation in the regeneration model.

Conclusion

Our data suggests a functional role of CLDN3 for maintenance of energy homeostasis and optimal regeneration, proving that the function of hepatic tight junction proteins extends beyond basic membrane sealing.

Central GABAA receptor mediates taurine-induced hypothermia and possibly reduces food intake in thermo-neutral chicks and regulates plasma metabolites in heat-exposed chicks

The aim of this study was to examine the central action of taurine on body temperature and food intake in neonatal chicks under control thermoneutral temperature (CT) and high ambient temperature (HT). Intracerebroventricular injection of taurine caused dose-dependent hypothermia and reduced food intake under CT. The mRNA expression of the GABA_A receptors, GABA_AR-α1 and GABA_AR-γ, but not that of GABA_BR, significantly decreased in the diencephalon after central injection of taurine. Subsequently, we found that picrotoxin, a GABA_AR antagonist, attenuated taurine-induced hypothermia. Central taurine significantly decreased the brain concentrations of 3-methoxy-4-hydroxyphenylglycol, a major metabolite of norepinephrine; however, the concentrations of serotonin, dopamine, and the epinephrine metabolites, 3,4-hydroxyindoleacetic acid and homovanillic acid, were unchanged. Although hypothermia was not observed under HT after central injection of taurine, plasma glucose and uric acid levels were higher, and plasma sodium and calcium levels were lower, than those in chicks under CT. In conclusion, brain taurine may play a role in regulating body temperature and food intake in chicks through GABA_AR. The changes in plasma metabolites under heat stress suggest that brain taurine may play an important role in maintaining homeostasis in chicks.

Photoperiodic changes in hippocampal neurogenesis and plasma metabolomic profiles in relation to depression-like behavior in mice

Photoperiod alters affective behaviors and brain neuroplasticity in several mammalian species. We addressed whether neurogenesis and signaling pathways of insulin-like growth factor-I (IGF-I), a key modulator of neuroplasticity, are regulated by photoperiod in C57BL/6 J mice, a putative model of seasonal affective disorder. We also examined the effects of photoperiod on plasma metabolomic profiles in relation to depression-like behavior to understand a possible linkage between peripheral metabolism and behavior. Mice that were maintained under long-day conditions (LD) exhibited a higher number of 5-bromo-2'-deoxyuridine-positive cells and higher levels of astrocyte marker in the dentate gyrus of the hippocampus compared to that of mice under short-day conditions (SD). Plasma IGF-I levels and levels/expression of IGF-I signaling molecules in the hippocampus (Brn-4, NeuroD1, and phospho-Akt) involved in neuronal proliferation and differentiation were higher in the mice under LD. Metabolome analysis using plasma of the mice under LD and SD identified several metabolites that were highly correlated with immobility in the forced swim test, a depression-like behavior. Negative correlations with behavior occurred in the levels of 23 metabolites, including metabolites related to neurogenesis and antidepressant-like effects of exercise, metabolites in the biosynthesis of arginine, and the occurrence of branched chain amino acids. Three metabolites had positive correlations with the behavior, including guanidinosuccinic acid, a neurotoxin. Taken together, photoperiodic responses of neurogenesis and neuro-glial organization in the hippocampus may be involved in photoperiodic alteration of depression-like behavior, mediated through multiple pathways, including IGF-I and peripheral metabolites.

Potential Role of Amino Acids in the Adaptation of Chicks and Market-Age Broilers to Heat Stress

Increased average air temperatures and more frequent and prolonged periods of high ambient temperature (HT) associated with global warming will increasingly affect worldwide poultry production. It is thus important to understand how HT impacts poultry physiology and to identify novel approaches to facilitate improved adaptation and thereby maximize poultry growth, health and welfare. Amino acids play a role in many physiological functions, including stress responses, and their relative demand and metabolism are altered tissue-specifically during exposure to HT. For instance, HT decreases plasma citrulline (Cit) in chicks and leucine (Leu) in the embryonic brain and liver. The physiological significance of these changes in amino acids may involve protection of the body from heat stress. Thus, numerous studies have focused on evaluating the effects of dietary administration of amino acids. It was found that oral l-Cit lowered body temperature and increased thermotolerance in layer chicks. When l-Leu was injected into fertile broiler eggs to examine the cause of reduction of Leu in embryos exposed to HT, in ovo feeding of l-Leu improved thermotolerance in broiler chicks. In ovo injection of l-Leu was also found to inhibit weight loss in market-age broilers exposed to chronic HT, giving rise to the possibility of developing a novel biotechnology aimed at minimizing the economic losses to poultry producers during summer heat stress. These findings and the significance of amino acid metabolism in chicks and market-age broilers under HT are summarized and discussed in this review.

Intracerebroventricular injection of L-arginine and D-arginine induces different effects under an acute stressful condition

Central administration of L-arginine was reported to attenuate stress responses in neonatal chicks. The present study aimed to elucidate the differential effects of centrally administered L-arginine and its enantiomer, D-arginine, on the stress response in chicks and the associated mechanisms. Intracerebroventricular injection of L-arginine attenuated acute isolation stress by inducing sleep-like behavior, while central administration of D-arginine potentiated the stress response, reducing the time spent standing motionless with eyes open and increasing distress vocalizations compared to the control. The brain concentrations of amino acids and monoamines following L- and D-arginine administration during stress were also determined. L-Arginine significantly increased the mesencephalic L-glutamine concentration. D-Arginine administration did not affect the levels of L-arginine or other amino acids in the examined brain regions. 3,4-Dihydroxyphenylacetic acid (DOPAC) level and dopamine (DA) metabolic rate (DOPAC/DA) were significantly higher in the diencephalon in the D-arginine group compared to the L-arginine group, while the mesencephalic DA level was significantly lower in the D-arginine group compared to the control. In vitro experiment using the brain slice culture demonstrated that extracellular perfusion of D-arginine significantly elevated the mRNA expression level of monoamine oxidase B, the major enzyme involved in DA metabolism, in the locus coeruleus region of the brainstem. In conclusion, in neonatal chicks, central administration of D-arginine exerted a stimulant effect on the stress response, in contrast to the stress-attenuating effects of L-arginine, partly through an effect on brain dopaminergic metabolism and not through competition with the L-stereoisomer.

Orally administrated D-arginine exhibits higher enrichment in the brain and milk than L-arginine in ICR mice

D-Amino acids exert various physiological functions and are widely present in animals. However, they are absorbed to a lesser extent than L-amino acids. Little is known about D-arginine (D-Arg); however, its isomer L-Arg serves as a substrate for several metabolites and exhibits various functions including promotion of growth hormone secretion. Milk is the only nutrient source for infants; it plays an important role during their initial growth and brain development. No studies have evaluated the availability of D-Arg in the brain and milk in mammals. Here, we have studied the differential availability of orally administered D- and L-Arg in the brain and milk using ICR mice. Our results revealed that without D-Arg administration, D-Arg was undetectable in both plasma and brain samples. However, the plasma D-Arg was about twice the concentration of L-Arg post administration of the same. In the cerebral cortex and hypothalamus, L-Arg concentration remained almost constant for over period of 90 min after L-Arg treatment. Nevertheless, the L-Arg concentration decreased after D-Arg administration with time compared to the case post L-Arg administration. Contrastingly, D-Arg level sharply increased at both the brain regions with time after D-Arg treatment. Furthermore, L-Arg concentration in the milk hardly increased after L-Arg administration. Interestingly, oral administration of D-Arg showed efficient enrichment of D-Arg in milk, compared with L-Arg. Thus, our results imply that D-Arg may be available for brain development and infant nourishment through milk as an oral drug and/or nutrient supplement.

Effects of Chattonella antiqua on the swimming behavior and brain monoamine metabolism of juvenile yellowtail (Seriola quinqueradiata)

Being the precursor of serotonin and melatonin, dietary supplementation with tryptophan (TRP) may modulates behavior, stress responses, and antioxidant capacity in fish. In this study, effects of Chattonella exposure on the swimming behavior and brain monoamine metabolism of yellowtail fed a commercial diet (control diet) or that enriched by 1.5% L-TRP (TRP + diet) were investigated. A 7-day dietary TRP supplementation elevated spontaneous swimming speed of yellowtail and mitigated their behavioral response to Chattonella (250 cells/mL) exposure. A 30-day dietary TRP supplementation elevated growth of juvenile yellowtail. Lethal exposure to Chattonella (1000 cells/mL) significantly elevated the turnover rates of serotonin, dopamine, and norepinephrine metabolism in fish fed control diet, but did not alter the serotonin turnover rate in fish fed TRP + diet. Our results suggested that dietary supplementation with TRP had potential to mitigate the stress response in yellowtail to Chattonella, partly via mediating their brain monoamine metabolism.

An acute increase in water temperature can increase free amino acid concentrations in the blood, brain, liver, and muscle in goldfish (Carassius auratus)

Water temperature directly affects the body temperature in fish, so increasing water temperatures in oceans and rivers will lead to increases in fish body temperatures. Whilst a range of responses of fish to increases in water temperature have been measured, amino acid metabolism in a fish under high water temperature (HT) conditions has not been investigated. The aim of this study was to determine the effects of an acute increase in water temperature on oxygen consumption, plasma cortisol concentrations, and free amino acid concentrations in plasma and several tissues in goldfish (Carassius auratus). Oxygen consumption and plasma cortisol concentrations were increased in goldfish exposed to HT (30 ± 1 °C) for 200 min compared with goldfish at a control water temperature (CT 17 ± 1 °C). Oxygen consumption and plasma cortisol concentrations in both groups of fish combined were positively correlated. When goldfish were exposed to HT for 300 min oxygen consumption and plasma concentrations of 15 free amino acids were increased compared with goldish at CT. Concentrations of several free amino acids were increased to varying extents in the brain, liver, and muscle tissues. In conclusion, an acute increase in water temperature affected amino acid metabolism differently in the brain, liver, and muscle tissues. Goldfish will be a useful species for further studies of the possible roles of various amino acids in the brain, muscle, and liver during acute increases in water temperature in fish.

Decreased stress-induced depression-like behavior in lactating rats is associated with changes in the hypothalamic-pituitary-adrenal axis, brain monoamines, and brain amino acid metabolism

Depression-like behavior during lactation may relate to changes in the hypothalamic-pituitary-adrenal (HPA) axis, brain monoamines, and brain amino acid metabolism. This study investigated how the behavior, HPA axis activity, brain monoamines, and brain free amino acid metabolism of rats were changed by stress or lactation period. Rats were separated into four groups: (1) control lactating (n = 6), (2) stress lactating (n = 6), (3) control virgin (n = 7), and (4) stress virgin (n = 7) and restrained for 30 min a total of ten times (once every other day) from postnatal day (PND) 1. Depression-like behavior in the forced swimming test (FST) on PND 10 and concentration of corticosterone in plasma, as well as monoamines and L-amino acids including β-alanine, γ-aminobutyric acid, cystathionine, 3-methyl-histidine and taurine in the prefrontal cortex and hypothalamus on PND 19 were measured. The plasma corticosterone concentration, measured just after restraint stress, was significantly higher in the stress groups, versus the control groups, but there were no significant differences between control and stress lactating groups. Depression-like behavior (immobility) in the FST was significantly lower in the lactating groups, versus the virgin groups. Stress enhanced dopamine and glutamate, and decreased threonine and glycine concentrations in the hypothalamus. In addition, 3-methoxy-4-hydroxyphenylglycol (MHPG), threonine and ornithine concentrations in the prefrontal cortex were significantly higher in the lactating groups compared with the virgin groups. Changes in plasma corticosterone concentration, monoamine, and amino acid metabolism may relate to stress-induced depression-like behavior in lactating rats. Lay summary This study revealed that reduced depression-like behavior in lactating, relative to virgin rats, was associated with changes in monoamine and amino acid metabolism in the prefrontal cortex of the brain. In addition, the effect of stress on monoamine and amino acid metabolism is prominently observed in the hypothalamus and may be related to neuroendocrine stress axis activity and secretion of corticosterone. This study suggested that stress-induced depression-like behavior may be associated with several changes in the stress axis, brain monoamines, and brain amino acid metabolism. These parameters were associated with attenuated depression-like behavior in lactating rats.

Differences in free amino acid concentrations in milk between Wistar and Wistar Kyoto rats

Wistar Kyoto (WKY) rats, an animal depression model, display abnormal behaviors such as hypoactivity and depression-like behavior compared with Wistar (WIS) rats as a control. A previous study confirmed a dysfunction of amino acid metabolism in the brain of WKY rats compared with that of WIS rats. At the neonatal stage, free amino acids in milk are important nutrients because they act as immediate nutrients for offspring and may affect later health and behavior of the offspring. Therefore, the present study aimed to investigate free amino acid concentrations in milk and the relationships between free amino acid concentrations in milk and plasma in WIS and WKY rats. The concentrations of ten of the determined free amino acids in milk were significantly higher, but only L-methionine was significantly lower, in WKY rats. Six free amino acids had significantly higher concentrations in colostrum and two free amino acids had higher concentrations in matured milk. Free amino acid concentrations in plasma changed by both genetic background and lactation stage; however, the patterns of change in most free amino acid concentrations except for taurine in plasma were similar between WIS and WKY rats. The transport ratio of free amino acids from plasma to milk was not similar among the free amino acids tested, and each free amino acid was influenced by the genetic background and/or the type of milk.

L-Leucine increases the daily body temperature and affords thermotolerance in broiler chicks

OBJECTIVE

Heat stress poses an increasing threat for poultry production. Some amino acids have been found to play critical roles in affording thermotolerance. Recently, it was found that in ovo administration of L-leucine (L-Leu) altered amino acid metabolism and afforded thermotolerance in heat-exposed broiler chicks.

METHODS

In this study, two doses (35 and 70 μmol/egg) of L-Leu were administered in ovo on embryonic day 7 to determine their effect on rectal temperature (RT), body weight (BW) and thyroid hormones at hatching. Changes in RT, BW, and thermotolerance in post-hatched chicks were also analyzed.

RESULTS

It was found that in ovo administration of L-Leu dose-dependently reduced RT and plasma thyroxine (T4) level just after hatching. In post-hatched neonatal broiler chicks, however, the higher dose of L-Leu administered in ovo significantly increased RT without affecting BW gain. In chicks that had been exposed to heat stress, the RT was significantly lowered by in ovo administration of L-Leu (high dose) in comparison with the control chicks under the same high ambient temperature (HT: 35°C±1°C, 120 min).

CONCLUSION

In ovo administration of L-Leu in a high dose contributed to an increased daily body temperature and afforded thermotolerance under HT in neonatal broiler chicks.

Flavangenol regulates gene expression of HSPs, anti-apoptotic and anti-oxidative factors to protect primary chick brain cells exposed to high temperature

Heat-stress exposure increased the expression of heat-shock proteins (HSPs), B-cell lymphoma 2 (BCL-2) and anti-oxidative enzymes to maintain normal cellular function by attenuating the oxidative reaction and apoptosis. Reducing the stress response or enhancing anti-stress capability is an important goal in animal production. Our previous study indicated a protective role of flavangenol, a pine bark extract, in chicks after three hours of high-temperature exposure. However, the cellular mechanism of flavangenol was not clarified ex vivo. In the current study, we investigated the effect of flavangenol on cellular apoptosis and oxidation in heat-stressed treated chick brain cells (mixed neurons and glia cells). The primary brain cells were isolated from the diencephalon of 14-day-old chicks and cultured at 41.5 °C (to mimic the body temperature of young chicks), and were treated with flavangenol from day 3 of isolation to day 8. Cells were kept bathed in the cell culture dish under a high temperature (HT: 45 °C, 20 or 60 min) on day 8 and were then collected for analysis of cell viability as well as for HSP and other related gene expression. Flavangenol treatment significantly increased cell viability and BCL-2 mRNA expression, and attenuated HSP-70 and BCL-2-associated X protein mRNA expression. Moreover, flavangenol treatment elevated the mRNA expression of glutathione peroxidase in the HT group, which indicates that cellular anti-oxidative ability was strengthened by flavangenol. In conclusion, flavangenol may play a protective role in cells damaged or killed by heat stress by increasing cellular anti-oxidative pathways.

Reduction in voluntary food intake, but not fasting, stimulates hypothalamic gonadotropin-inhibitory hormone precursor mRNA expression in chicks under heat stress

Heat stress is an issue of rising concern across the globe. Recently, we found that mRNA expression of gonadotropin-inhibitory hormone (GnIH), an orexigenic neuropeptide, was increased in the heat-exposed chick brain when food intake was reduced. The aim of the current study was to examine mRNA expression of GnIH and of the glucocorticoid receptors (GRs) in the hypothalamus as well as the plasma corticosterone (CORT) and metabolites in 14-d-old chicks exposed to a high ambient temperature (HT; 40 ± 1 °C for 1 or 5 h) or a control thermoneutral temperature (CT; 30 ± 1 °C), either with free access to food or fasted. Heat stress caused a voluntary reduction of food intake and reduced plasma triacylglycerol concentration, but increased rectal temperature and plasma CORT and glucose concentrations (P < 0.05). Heat stress also increased (P < 0.05) the expression of diencephalic GnIH mRNA in chicks when they reduced food intake voluntarily, but did not do so under fasting conditions. Although the expression of GR mRNA was not altered as a result of heat stress, its expression was decreased (P < 0.05) in fasted chicks at 5 h in comparison with fed chicks. In addition, the rectal temperature of fasted chicks was lower than that of fed chicks under both CT and HT. In conclusion, voluntary reduction of food intake caused an increase in brain GnIH mRNA expression, plasma CORT, and body temperature in chicks under heat stress. Interestingly, brain GnIH mRNA expression was not induced by heat stress in fasted chicks and was not accompanied by a decrease in rectal temperature. These results suggest that the increased expression of brain GnIH mRNA in chicks under heat stress could be a consequence of a mechanism mediated by the voluntary reduction of food intake, but that it is not a consequence of fasting.

Central NPY-Y5 sub-receptor partially functions as a mediator of NPY-induced hypothermia and affords thermotolerance in heat-exposed fasted chicks

Exposure of chicks to a high ambient temperature (HT) has previously been shown to increase neuropeptide Y (NPY) mRNA expression in the brain. Furthermore, it was found that NPY has anti‐stress functions in heat‐exposed fasted chicks. The aim of the study was to reveal the role of central administration of NPY on thermotolerance ability and the induction of heat‐shock protein (HSP) and NPY sub‐receptors (NPYSRs) in fasted chicks with the contribution of plasma metabolite changes. Six‐ or seven‐day‐old chicks were centrally injected with 0 or 375 pmol of NPY and exposed to either HT (35 ± 1°C) or control thermoneutral temperature (CT: 30 ± 1°C) for 60 min while fasted. NPY reduced body temperature under both CT and HT. NPY enhanced the brain mRNA expression of HSP‐70 and ‐90, as well as of NPYSRs‐Y5, ‐Y6, and ‐Y7, but not ‐Y1, ‐Y2, and ‐Y4, under CT and HT. A coinjection of an NPYSR‐Y5 antagonist (CGP71683) and NPY (375 pmol) attenuated the NPY‐induced hypothermia. Furthermore, central NPY decreased plasma glucose and triacylglycerol under CT and HT and kept plasma corticosterone and epinephrine lower under HT. NPY increased plasma taurine and anserine concentrations. In conclusion, brain NPYSR‐Y5 partially afforded protective thermotolerance in heat‐exposed fasted chicks. The NPY‐mediated reduction in plasma glucose and stress hormone levels and the increase in free amino acids in plasma further suggest that NPY might potentially play a role in minimizing heat stress in fasted chicks.

Usefulness of the 99mTc-MDP Scan in the Detection of Calcified Liver Metastases

A 99mTc-MDP scan was done on a patient with liver metastases from a medullary thyroid carcinoma who, in addition, had a familial history of multiple endocrine neoplasm, type 2. The scan revealed accumulation in several areas of calcified liver metastases.

Restraint stress in lactating mice alters the levels of sulfur-containing amino acids in milk

It is well known that maternal stress during the gestation and lactation periods induces abnormal behavior in the offspring and causes a lowering of the offspring’s body weight. Various causes of maternal stress during the lactation period, relating to, for example, maternal nutritional status and reduced maternal care, have been considered. However, little is known about the effects on milk of maternal stress during the lactation period. The current study aimed to determine whether free amino acids, with special reference to sulfur-containing amino acids in milk, are altered by restraint stress in lactating mice. The dams in the stress group were restrained for 30 min at postnatal days 2, 4, 6, 8, 10 and 12. Restraint stress caused a reduction in the body weight of lactating mice. The concentration of taurine and cystathionine in milk was significantly higher in the stress group, though stress did not alter their concentration in maternal plasma. The ratio of taurine concentration in milk to its concentration in maternal plasma was significantly higher in the stress group, suggesting that stress promoted taurine transportation into milk. Furthermore, taurine concentration in milk was positively correlated with corticosterone levels in plasma. In conclusion, restraint stress in lactating mice caused the changes in the metabolism and in the transportation of sulfur-containing amino acids and resulted in higher taurine concentration in milk. Taurine concentration in milk could also be a good parameter for determining stress status in dams.

Dietary L-serine modifies free amino acid composition of maternal milk and lowers the body weight of the offspring in mice

The growth of offspring is affected not only by the protein in maternal milk but also by the free amino acids (FAAs) contained in it. L-Serine (L-Ser) is known as an important FAA for the development of the central nervous system and behavioral activity. However, it is not clear whether L-Ser is transported into the pool of FAAs contained in milk and thereby affects the growth of offspring. Using mice, the current study investigated the effects of dietary L-Ser during pregnancy and lactation on milk and plasma FAA composition, as well as on growth, behavior, and plasma FAAs of offspring. Dietary L-Ser did not significantly affect the maternal, anxiety-like, or cognitive behaviors of either the dam or the offspring. The FAA composition notably differed between plasma and milk in dams. In milk, dietary L-Ser increased free L-Ser levels, while glutamic acid, L-alanine, D-alanine and taurine levels were decreased. The body weight of the offspring was lowered by dietary L-Ser. The concentrations of plasma FAAs in 13-day-old offspring (fed only milk) were not altered, but 20-day-old offspring (fed both milk and parental diet) showed higher plasma L-Ser and D-Ser concentrations as a result of the dietary L-Ser treatment. In conclusion, the present study found that dietary L-Ser transported easily from maternal plasma to milk and that dietary L-Ser treatment could change the FAA composition of milk, but that an enhanced level of L-Ser in milk did not enhance the plasma L-Ser level in the offspring.

l-Serine Enhances Light-Induced Circadian Phase Resetting in Mice and Humans

Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood.Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans.Methods: Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before l-serine administration, and light-induced phase shifts were analyzed. In addition, the effect of l-serine on the light-induced phase advance was investigated in healthy male students (mean ± SD age 22.2 ± 1.8 y) by using dim-light melatonin onset (DLMO) determined by saliva samples as an index of the circadian phase.Results: l-Serine administration enhanced light-induced phase shifts in mice (1.86-fold; P < 0.05). Both l-serine and its metabolite d-serine, a coagonist of N-methyl-d-aspartic acid (NMDA) receptors, exerted this effect, but d-serine concentrations in the hypothalamus did not increase after l-serine administration. The effect of l-serine was blocked by picrotoxin, an antagonist of γ-aminobutyric acid A receptors, but not by MK801, an antagonist of NMDA receptors. l-Serine administration altered the long-term expression patterns of clock genes in the suprachiasmatic nuclei. After advancing the light-dark cycle by 6 h, l-serine administration slightly accelerated re-entrainment to the shifted cycle. In humans, l-serine ingestion before bedtime induced significantly larger phase advances of DLMO after bright-light exposure during the morning (means ± SEMs-l-serine: 25.9 ± 6.6 min; placebo: 12.1 ± 7.0 min; P < 0.05).Conclusion: These results suggest that l-serine enhances light-induced phase resetting in mice and humans, and it may be useful for treating circadian disturbances.

Intraoperative 5-aminolevulinic acid-induced photodynamic diagnosis of metastatic brain tumors with histopathological analysis

BACKGROUND

Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is a promising real-time navigation method in the surgical resection of malignant gliomas. In order to determine whether this method is applicable to metastatic brain tumors, we evaluated the usefulness of intraoperative fluorescence patterns and histopathological features in patients with metastatic brain tumors.

METHODS

We retrospectively reviewed the cases of 16 patients with metastatic brain tumors who underwent intraoperative 5-ALA fluorescence-guided resection. Patients were given 20 mg/kg of 5-ALA orally 2 h prior to the surgery. High-powered excitation illumination and a low-pass filter (420, 450, or 500 nm) were used to visualize the fluorescence of protoporphyrin IX (PpIX), the 5-ALA metabolite. We evaluated the relationships between the fluorescence and histopathological findings in both tumoral and peritumoral brain tissue.

RESULTS

Tumoral PpIX fluorescence was seen in only 5 patients (31%); in the remaining 11 patients (69%), there was no fluorescence in the tumor bulk itself. In 14 patients (86%), vague fluorescence was seen in peritumoral brain tissue, at a thickness of 2-6 mm. The histopathological examination found cancer cell invasion of adjacent brain tissue in 75% of patients (12/16), at a mean ± SD depth of 1.4 ± 1.0 mm (range 0.2-3.4 mm) from the microscopic border of the tumor. There was a moderate correlation between vague fluorescence in adjacent brain tissue and the depth of cancer cell invasion (P = 0.004).

CONCLUSION

Peritumoral fluorescence may be a good intraoperative indicator of tumor extent, preceding more complete microscopic gross total resection.

TRIAL REGISTRATION

Institutional Review Board of Osaka Medical College No. 42, registered February 17, 1998, and No. 300, registered April 1, 2008. They were retrospectively registered.

Exposure of C57BL/6J mice to long photoperiod during early life stages increases body weight and alters plasma metabolomic profiles in adulthood

Perinatal photoperiod is an important regulator of physiological phenotype in adulthood. In this study, we demonstrated that postnatal (0–4 weeks old) exposure of C57BL/6J mice to long photoperiod induced persistent increase in body weight until adulthood, compared with the mice maintained under short photoperiod. The expression of peroxisome proliferator‐activated receptor δ, a gene involved in fatty acid metabolism, was decreased in 10‐week‐old mice exposed to long photoperiod during 0–4 or 4–8 weeks of age. Plasma metabolomic profiles of adult mice exposed to a long photoperiod during the postnatal period (0–4 LD) were compared to those in the mice exposed to short photoperiod during the same period. Cluster analysis revealed that both carbon metabolic pathway and nucleic acid pathway were altered by the postnatal photoperiod. Levels of metabolites involved in glycolysis were significantly upregulated in 0–4 LD, suggesting that the mice in 0–4 LD use the glycolytic pathway for energy expenditure rather than the fatty acid oxidation pathway. In addition, the mice in 0–4 LD exhibited high levels of purine metabolites, which have a role in neuroprotection. In conclusion, postnatal exposure of C57BL/6J mice to long photoperiod induces increase in body weight and various changes in plasma metabolic profiles during adulthood.

Slow-Myofiber Commitment by Semaphorin 3A Secreted from Myogenic Stem Cells

Recently, we found that resident myogenic stem satellite cells upregulate a multi-functional secreted protein, semaphorin 3A (Sema3A), exclusively at the early-differentiation phase in response to muscle injury; however, its physiological significance is still unknown. Here we show that Sema3A impacts slow-twitch fiber generation through a signaling pathway, cell-membrane receptor (neuropilin2-plexinA3) → myogenin-myocyte enhancer factor 2D → slow myosin heavy chain. This novel axis was found by small interfering RNA-transfection experiments in myoblast cultures, which also revealed an additional element that Sema3A-neuropilin1/plexinA1, A2 may enhance slow-fiber formation by activating signals that inhibit fast-myosin expression. Importantly, satellite cell-specific Sema3A conditional-knockout adult mice (Pax7CreER^T2 -Sema3A^fl °^x activated by tamoxifen-i.p. injection) provided direct in vivo evidence for the Sema3A-driven program, by showing that slow-fiber generation and muscle endurance were diminished after repair from cardiotoxin-injury of gastrocnemius muscle. Overall, the findings highlight an active role for satellite cell-secreted Sema3A ligand as a key "commitment factor" for the slow-fiber population during muscle regeneration. Results extend our understanding of the myogenic stem-cell strategy that regulates fiber-type differentiation and is responsible for skeletal muscle contractility, energy metabolism, fatigue resistance, and its susceptibility to aging and disease. Stem Cells 2017;35:1815-1834.

Central administration of neuropeptide Y differentially regulates monoamines and corticosterone in heat-exposed fed and fasted chicks

Recently, we demonstrated that brain neuropeptide Y (NPY) mRNA expression was increased in heat exposed chicks. However, the functions of brain NPY during heat stress are unknown. This study was conducted to investigate whether centrally administered NPY affects food intake, rectal temperature, monoamines, stress hormones and plasma metabolites in chicks under high ambient temperatures (HT). Five or six-day-old chicks were centrally injected with 0, 188 or 375pmol of NPY and exposed to either HT (35±1°C) or a control thermoneutral temperature (CT; 30±1°C) for 3h whilst fed or fasted. NPY increased food intake under both CT and HT. NPY reduced rectal temperature 1 and 2h after central administration under CT, but not under HT. Interestingly, NPY decreased brain serotonin and norepinephrine concentrations in fed chicks, but increased concentrations of brain dopamine and its metabolites in fasted and fed chicks, respectively. Plasma epinephrine was decreased by NPY in fed chicks, but plasma concentrations of norepinephrine and epinephrine were increased significantly by NPY in fasted-heat exposed chicks. Furthermore, NPY significantly reduced plasma corticosterone concentrations in fasted chicks. Plasma glucose and triacylglycerol were increased by NPY in fed chicks, but triacylglycerol declined in fasted NPY-injected chicks. In conclusion, brain NPY may attenuate the reduction of food intake during heat stress and the increased brain NPY might be a potential regulator of the monoamines and corticosterone to modulate stress response in heat-exposed chicks.

Effects of nutritional status on hormone concentrations of the somatotropin axis and metabolites in plasma and colostrum of Japanese Black cows

We aimed to determine the effects of nutritional status on concentrations of somatotropic axis hormones (growth hormone (GH) and insulin-like growth factor 1 (IGF-1)), insulin and metabolites (glucose, total protein and nonesterified fatty acids (NEFA)) in the plasma and colostrum in late antepartum cows. Eight pregnant Japanese Black cows were randomly assigned to two experimental groups (n = 4 per group). Control cows (CON) received 100% of their nutritional requirements until parturition, whereas restricted group cows (RES) received 60% of their nutritional requirements. Blood samples were taken during the antepartum period, and blood and colostrum samples were collected on days 0, 1, and 3 after calving. Compared to the CON group, the RES group had higher concentrations of GH and NEFA in plasma, but significantly lower concentrations of glucose and insulin in plasma. The concentrations of GH in plasma after calving were significantly higher, but total plasma protein was significantly lower in RES than in CON cows. Compared to the CON group, the RES group had significantly higher concentrations of GH in colostrum, but significantly lower total concentrations of protein in colostrum. Concentrations of IGF-1 were not different between the two groups. These findings suggest that maternal nutritional status during late gestation influences concentrations of GH and total protein in the blood and colostrum of Japanese Black cows.